Influence of (C1236T and C3435T) Polymorphisms of ABCB1 Gene on Chemotherapy Treatment Outcome and Toxicity in Breast Cancer Patients.

Background: ATP Binding Cassette Transporters (ABCB1) gene plays an important role in transport of different metabolites and anticancer drugs across the cell membrane. There is lack of knowledge on ABCB1 gene polymorphism and its correlation with Adriamycin or paclitaxel based chemotherapy induced toxicity in breast cancer patients. Therefore in this study, we explored the correlation of ABCB1 polymorphisms gene on response and toxicity in adriamycin and paclitaxel based chemotherapy in breast cancer patients from Indian population.

Methods: Two hundred BC patients receiving Adriamycin and paclitaxel chemotherapy were enrolled in this study and chemotherapy induced hematological and non-hematological toxicity reactions were noted. The polymorphisms in ABCB1 gene (C1236T, C3435T) were studied by PCR and RFLP analysis.

Results: The univariate logistic regression analysis showed statistically significant negative association with protective effects of ABCB1 (C3435T) polymorphism with heterozygous genotype (OR=0.34, 95% CI: 0.13-0.89; p=0.027), homozygous variant genotype (OR=0.31, 95% CI: 0.10-0.99; p=0.049) and combined C/T+T/T genotypes (OR=0.33, 95% CI: 0.13-0.79; p=0.013) in relation with severe toxicity of chemotherapy induced nausea and vomiting in breast cancer patients treated with Adriamycin chemotherapy. The 3435 C>T polymorphism of ABCB1 gene with heterozygous C/T genotype showed significantly negative association (OR=0.37, 95% CI: 0.14-0.96; p=0.042) with peripheral neuropathy in patients treated primarily with paclitaxel thereafter Adriamycin.

Conclusion: The findings obtained from this study revealed significant association of ABCB1 3435 C>T polymorphisms with non-hematological toxicity in response to adriamycin and paclitaxel based chemotherapy.